Apparatus for stabilizing well drills



D n 7. 1954 E. J. ROBISHAW 2,695,367

APPARATUS FOR STABILIZING WELL DRILLS Filed May 13, 1949 5 Sheets-Sheet 1 A la. W 2'2 i\ II a v i 3,. i 8

mm 5M2 QMJM E51. -i j m Dec. 7, 1954 ROBlSHAw 2,696,367

APPARATUS FOR STABILIZING WELL DRILLS Filed May 15, 1949 3 Sheets-Sheet 2 a. mafia Dec. 7, 1954 E. J. ROBISHAW 2,696,367

APPARATUS FOR STABILIZING WELL DRILLS Filed May 15, 1949 3 Sheets-Sheet 5 ..K FE A AQYAQY QY & b 7

flTTOR/VEK I bit and particularly an apparatus terial fromthe bottom of the bore, hole of irregular transverse dimensions.

United States Patent 2,696,367 APPARATUS non srnnrnznsc wnrr. :DR'HJLS Earl J. Robishaw, Houston, Tern, assignor to --A-1 tBit 19a Tool Company, Houston, Tex, acorporation of Texas Application May 13, 1949, Serial No. 92,998 4 Claims. ((1255-23) This invention relates to the art of drilling wells by by the employment of a rotary stem provided with a for stabilizing the drill. yIn drilling wells or bore holes in the earth various types of formations are encountered and in' drilling through them the drill the axis of the bore.

does-not necessarily rotate about This is particularly true as the drill stem becomes lengthened as the well is deepened since there 1s a certain amount of flexibility in stem.

. Int-other words the drill often wabbles and forms a bore hole of much greater transverse diameter than the the drill "transverse diameter of the-drill. This delays the. progress of, the work, causes unnecessary removal of earth maand. forms a bore The drilling assembly used 'n drilling a well is made up of a drill bit which is connected to the lower end of the drill stem by means of a drill collar or collars. The overall transversediameter of the drill is the same as the transverse diameter of the. bore hole while the transverse diameter of the drill collar is somewhat less than said diameter of the. drill and the transverse diameter of the drill stem is considerably less than the transverse diameter of the drill collar, So the only part of the assembly which is of the same transverse diameter asthe bore hole is the drill itself. The drill is relatively short and is in contact with the walls of the bore hole for a relatively short distance, usually not morethan twelve inches, and inmost cases of less distance. It is, therefore, apparent that the drill collar can move from the axial center of the bore hole in all directions, and if the drill bit starts drifting it will drift progressively off-center witl'ioutany "hindrance except the tendency which might be described 'as a plumb bob effect the heavy drill collar on the bottomof' the produced by relatively light drill pipe. It will further be seen that the greater the weight sustained by the drill the greater is the tendency for the bore hole to drift away from vertical.

In addition to the drifting effect, there are other conditions which prevail while drilling certainty'pe's of formation such, for example, as sandy shale. Under such conditions the drill bit may startoscillating and assume a regular oscillatory movement such that it will drill an out-of-round hole? It a fish tail bit is employed the hole will be substantially triangular in horizontal cross-section. If a three-way bit is employed the hole will be substantially square. In the case of a tricone rock drill the hole can be drilled substantially square in horizontal cross-section. Such holes while being drilled would not allow the passage of a round object of the same maximum transverse diameter of the drill being used because the minimum distance from one wall to the opposite one would be less than the maximum transverse diameter of the drill itself.

Another condition which often arises while drilling of.--the hole and one side is continuously in contact 2 with: the: wall. of the well bore. When this condition arises the rate of penetration of the; drill bit drops to practically-- zero and the hole then drilled=1s oversized and extra'rformation is unnecessarily removed.

Because of the aforementioned" conditions, where the hole? drilledislarger than the drill itself and frequently many times as large, it followsthat much more material will: be drilled and to a greater volume than necessary to producethe desired bore hole. This not only decreases the efliciency of drillingmany fold, but results in. an undue enlargement'ofthe hole, aggravating caving and requiring" materially larger amounts of cement when a casing is: cemented.

One of the objects of this invention, therefore, is toprovide an apparatus whereby theabove disadvantages may be overcome;

It, is a further object of the invention to provide a stabilizer which will not drill but which merely floats on the drill stem, which will not resist in any manner upward or downward movement of the drilling tool, which will not retard circulation but will merely act as a stabilizer.

Under said conditions a single stabilizerimay' effectively maintain the drill bit centered with relation to the borehole so as to drill a straight bore while under other conditions two, or more, of the stabilizers may be required as will be more specifically hereinafter set out.

It is still a further object of the present invention to providestabilizingmeans whichiwill be effective to drill away the sidewall formation of the well in case the equipmentshould become stuck in withdrawing the same from the well bore, or in lowering it into the bore.

Other objects and advantages will be apparent from the following specification which is illustrated by the accompanying drawings disclosing an illustrative em bodiment of this invention; it is to be understood, however, that this invention is' susceptible of various other embodiments within the scope of the appended claims without departingfrom the'spirit of this invention. In the accompanying drawings: 7

Figure l is a vertical sectional view of the upper end of the stabilizer.

Figure 2 is a vertical sectional view of lower end thereof.

Figure 3 is a cross-sectional view taken on the line 3-'3 of Figure 1.

Figure. 4 is a cross sectional view taken 4-4 of Figure 2.

Figure 5-is an enlarged'fragmentary side elevationof the stabilizer show'nin-a well bore.

Figure 6 is a side view of the complete assembly shown in the well bore.

Figure 7 is a side elevation of the upper endof the complete assembly in which a plurality of stabilizers are employed.

Figure 8 is anelevationalview of an intermediate'portion of said assembly.

gigure 9 is aside elevation of the lower end thereof; an

Figure 10 is a vertical sectional view of 'the upper end ofanother embodiment of the stabilizer, shown in Figure 1.

Generally stated and in accordance with illustrative embodiments of this invention, the drill stem is centered by a bearingin the bore hole above the bit and this bearing; is released from the bore hole upon sticking thereof. This may be accomplished in various ways, such as by axialmovementof the drill stem by jarring thereof by relative axial impact of the drill stem and the bearingand by. clutching the bearing with the drillstem. The mechanism which may be employed for accomplishing the objectsof this invention may embody generally a drill stem section arranged for coupling as a part of a drilling equipment, such as with the drill pipe above" the section and with the bitbelow it. This drill stem'section has a-b'earin'g in which the section is relatively rotatable, the bearing being dimensioned to center the stern section inthe bore hole. Means is provided for releasing thebearingfrom the bore h'ole upon stickingther'eof; This may b'e accomplished invarious ways.

on the line In an illustrative embodiment, the bearing is relatively slidable as well as relatively rotatable with respect to the stem section, and this provides for means operating upon axial movement of the section to release the bearing from the bore hole. Means may, however, be: provided for clutching the bearing to the section either axially or rotatably, or both. Means is provided for jarring the section; thus, in an illustrative embodiment, this is accomplished by suddenly interrupting the relative sliding movement of the stem section and the bear-- ing. The bearing may, however, have included in it a shear so that upon relative movement of the stem section and the bearing, the hearing will be released.

Referring now more particularly to Figures 1 to 6, inelusive, of the drawings, the numeral 1 designates a tubular drill stem which extends to the ground surface. Incorporated into this drill stem there is what is commonly known as a drill collar 1a.

In the present illustration there is the tubular stabihzer stem 2 screwed onto the lower end of the drill collar 1a,. and attached to the lower end of the stabilizer stern there is a special coupling 3 to which any selected type of drill 4 may be connected.

It may be here stated that the drill collar 1a, the drill stem section or stabilizer stem 2, and the special coupling 3 all, in effect, are a part of the drill stem.

The upper end of stabilizer stem 2 is of approximately the same transverse diameter as that of the drill collar but it is reduced in transverse diameter forming the external, annular, downwardly facing shoulder 5 and on this shoulder there is an anti-friction thrust bearing assembly 6.

Beneath this bearing assembly around the stabilizer stem 2 there is the bearing in the form of an elongated cylindrical stabilizer sleeve 7.

Between this sleeve and the stem 2 there are a plurality of series of anti-friction rollers 8 so that said stem will rotate freely independent of the rotation of said sleeve. Between the sleeve 7 and stem 2 above and beneath said anti-friction rollers there are the upper and lower packing rings 9 and 10 to protect the anti-friction rollers against gritty substances.

On the sleeve 7, and spaced apart therearound, there are the stabilizing ribs 11, three of said ribs being shown although the number may vary. These ribs allow space for the return of the drilling fluid.

These ribs extend longitudinally of the sleeve and are preferably seated in grooves therein and are welded thereto; although they may be secured in place in any preferred manner.

are preferably quadrilateral in crosssection with their outer sides curved. Of course, the shape of the ribs may also vary. They radiate out from the sleeve so as to hold the sleeve with its axis approximately in coinciding relation with the axis of the bore.

The ribs 11 may be in the form of cutters hardened to present reaming cutters; however, these ribs may simply provide for engagement with the bore hole; and as later described may be of a friable material, such as cast iron or an aluminum alloy, or a plastic which is readily drillable.

The overall transverse diameter of the sleeve, including the ribs, is only slightly less than the transverse diameter of the bore hole so that the stem 2 and the drill will be maintained centered, or approximately centered, relative to the bore hole and this will prevent the drill from wabbling or wandering off of its true course.

The upper end of the coupling 3 is provided with J- slots spaced apart therearound. These slots are indicated by the numeral 12 and the lower end of the sleeve 7 is provided with the J-slots 13 which are reversely directed with respect to the slots 12. These slots 12 and 13 being spaced apart form projections 14 and 15 which project upwardly and downwardly, respectively, from the special coupling 3 and the sleeve 7.

Around the stabilizer stem 2 and seated within the projections 14 there is a strong coil spring 16 which forms a yieldable seat so as to prevent the projections 14, 15 from interengaging during normal drilling operations or when the drill stem is elevated relative to the sleeve 7.

In carrying on drilling operations the stabilizing ribs 11 will usually be in frictional contact with the walls of the well bore and the upper end of the stabilizing sleeve 7 will be in contact with the anti-friction hearing assembly 6.

However, when it is desired to lower the drill stem and drill into, or withdraw them from, the bore hole it may happen that the stabilizing sleeve will become stuck in a restriction in the bore or in a sidewall keyseat. In such event the drill stem may be pulled upwardly with sufiicient force to collapse the spring 16 so that the projections 14 will be brought into intermeshing relation with the projections 15 and upon rotation of the drill stem to the right said projections will interlock, by reason of the J-slots, thus forming a clutch so that the sleeve 7 will be caused to rotate with the drill stem and it will remain so interlocked while the drill stem is rotated and moved on down, or upwardly, so that the ribs will act as sidewall cutters to free the stuck stabilizer and the complete apparatus may be lowered on into, or withdrawn from, the well.

Described more extensively, it will be seen that the relative sliding movement of the bearing 7 and the drill stem section 2, which movement may be one or more feet in extent, provides for a jar. Thus assuming that the bearing 7 is stuck in the hole in the position shown in Figure 6, if the drill stem be nowraised, If the drill stem is now rotated, causing the coupling parts 12" and 13 to engage, there will be a further jar and this jar will be quite pronounced, because as the coupling 3 and the bearing have engaged there will be a tension placed on the drill stem so that when the couplings mesh they will snap together. Since the depth of the coupling recessses can be made two. or more inches, it will be seen that with the tension applied to the drill stem, the jar even here will be quite pronounced. Of

come the spring so that'there will be a pronounced jar. However, the tension of the drill pipe as the couplings far over-balance the pipe, so that if the bearing is the formation it will become so disengaged.

As hereinabove indicated two or more of the stabilizers may be required in order to maintain a straight bore hole. With one stabilizer it may happen that the upper end of the drill collar may wabble, and in such case, while the stabilizer may not wabble, the oscillating movement would be transmitted to the drill bit and cause it to move radially. In such case it would be necessary to locate an additional stabilizer above the drill collar assembly. This second stabilizer will stop the radial movement of the upper part of the drill collar and the lower stabilizer will stabilize the drill bit and true rotation of the drill bit would be had at all times. However, in case several drill collars were used it is possible for the complete assembly to wabble midway between the two stabilizers, which movement would be transmitted to the drill bit and in such case a third stabilizer would be required in order to eliminate this oscillating movement.

In the present illustration, as shown in Figures 7, 8 a d 9, three of said stabilizers are employed, one spaced above the drill, as shown in the other figures, such as in Figure 6, and the other stabilizers are spaced above any selected distance apart, said other stabilizers being type of stabilizer 7 and are incorporated into similar organizations.

In accordance with the embodiment, Figure 10, the bearing of sleeve 7 will be simply rotatably mounted on the stem section by the roller bearing therein as in Figure 1. There is, however, another ball thrust bearing 60, placed beneath the hearing so as to confine the same between these two thrust bearings, and this ball bearing 60 is retained by a collar 61. The slots for the cutters 11 which may be slidingly dovetailed into the bearing are then continued to the bottom of the bearing and retained by shear pins 62. It will be understood that in this embodiment the ball bearing 60 and the collar 61 are diametrically reduced so as to be inside the bottoms of the slots for the ribs or cutters 11. If in this case the bearing should become stuck, then by raising on the drill stem the pin 62 will shear so that the body of the bearing may be raised. This will, of course, leave the ribs or cutters 11 in the hole above the bit, but by raising of the bit, these will be displaced and by making the ribs of a friable material, such as cast iron, or of an aluminum silicon alloy, or of a plastic such as Bakelite, these ribs can be readily drilled out.

The drawings and description disclose what is now considered to be preferred forms of the invention by Way of illustration only and not by way of limitation, while the broad principle of the invention will be defined by the appended claims.

What I claim is:

1. In a drill stabilizer the combination comprising: a. drill stem to the lower end of which a drill is attached; a stabilizer sleeve mounted on said stem above the drill for rotative and axial movement relative to said stem; external longitudinal cutters on said sleeve for holding said stem approximately centered relative to a bore being drilled; and J-slot clutch means on said stem and sleeve, respectively, engagement of said clutch means causing said sleeve to rotate together and move axially with said stem, whereby the walls of the bore will be cut away upon rotation of said stem.

2. A stabilizer for drills comprising: a tubular stem to the lower end of which a drill is adapted to be attached; a sleeve mounted on said stem for rotative and axial movement relative thereto; external spacers mounted on said sleeve for drill-stem-centering engagement with the walls of a bore being drilled; and J-slot clutch means on said sleeve and said stem adapted, when engaged, to connect said sleeve and stem together for rotation and axial movement as a unit.

3. A stabilizer for drills comprising: a tubular stem to the lower end of which a drill is adapted to be attached;

a stabilizer sleeve mounted on said stem for rotative and axial movement relative thereto,

said sleeve having a plurality of longitudinal grooves; abutment means on said stem for limiting axial movement of said sleeve thereon; external spacers on said sleeve for drilling stem-centering engagement with the walls of a bore being drilled, said spacers comprising longitudinal ribs fitting in said sleeve grooves; and yieldable means including shearable pin means fastening said ribs to said sleeve.

4. A stabilizer for drills comprising: a tubular stem to the lower end of which a drill is adapted to be attached; a sleeve mounted on said stem for rotative and axial movement relative thereto; means on said stems for limiting said relative axial movement; external spacers mounted on said sleeve for drill-stem-centering engagement with the walls of a bore being drilled; and axiallyengageable clutch means mounted on said stem and said sleeve for connecting said sleeve to said stem for rotation in both directions therewith and for axial movement in both directions therewith.

References Cited in the file of this patent Number UNITED STATES PATENTS 

